Time announcement system



Jan. 21, 1936. B, F LEW|5 TIME ANNOUNCEMENT sYsTEM Filed Aug. 18, 1934MEM.. MJ

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l BY l I ATTORNEY Patented Jan. 21, 1936 UNITED- PATENT oFf-'Fftc-E TIMEANNQUNCEMEN SzY 'Benjamin F. 'Iiewisfllluslihg N/Y., .a'ss'ignor toAmericanTelephone and-| "Telegraph Company, acorporatibn of New YorkApplication ..August.18, 1934, SerialNo, 740;.497

` this invention is concerned; isk a onefway hspeech distribution systemby which information. con'- cerningthe time ofthe day is transmittedfrom a .central-bureau to various central offices of 1a telephone systemin order that such time information may be given to subscribers throughthose oilices. Amplifiers Vare provided Vin conneotionwith .the4transmitter at the timewbureau and, also, with the Various Vtrunkcircuits, in orderthat each subscribery requestingy time .service willreceive suchk information at the same transmission level as every othersubscriber; Sincefa time announcement system .must bein servicecontinuously throughout each day, it is necessary rthat all.transmission tests .vrequiredgto determine its transmission efficiency.be made without withdrawing thercircuits from service; One'of-the:objects of this" invention. is .to make transmission tests upon -a-time announcement system, the. tests being characterized by 'theemployment of the signal current, the-normal function of 'which is toindicate the exact :seco-nd of. time, for the .further purpose ofmeasuring the'transmission level` at the'output -oi theseveralyamplifiers associated with such system.

' Other .objects ofthis invention lWill be, appar' ent from thefollowing` description whenreadin connection with the attached' drawing.showing schematically a time announcement :systemiin which thepresentinvention is embodied;.

the.r drawing, the apparatus .and Tcircuits Withinthe' `dotted .linesdesignated AL lis located at ,fthe time bureau from which.information-concerning .the time ofthe day .is transmitted-Loyeratrnnkcircuitto a central: oi'ce such-as iserepresented. .by the.apparatus and circuitsA within the dotted lines designated B, `from`which` the information is distributed either Adirectly Ito subscribersat lthat oiice .or over other' trunk .circuits toidistant oices.. Theremay, of course, 4loe axpluralityloftofcessuch as B supplied froma single:time bureau and 4connected therewith.'v by transmission lines havingamplierszincrder'fto properly :maintain .the level of transmissionofsuch information .to .the subscribers;

.In making'. announcements 1in` ay system rsuch as thatwithfwhichlthisffinvention `is concerned, 'it 'is customary for 4an operator to:orally state". what the rt-,irneyvill .be upon theftransmis'si'on of yagiven sig-nallurepresentng,thetexactfsecondiof'that'time;

network 2.

The;:.transmitter, into which the operator speaks,

is representedby. -'I;. That transmitter, which is of Lthe high` qualitytype1isv connected to thetinput fof-a4 volume controlv network 12 which,in turn, is connected to transmitting; amplier. 3 .the output of whichis connected to the normal contacts of the relay 4. The given signa.referred toaboye is produced v'by the voscillator 5 which .is connectedthrough lthepotentiometer 6 tothe armaturesof the relay l. Thecontactsof A.that relay are `.connected to .the inner .contacts of relay 41. Theoscillator `is designed to generate a pure 800-cycle current Ybut 'such.current cannot be impressed vupon thesupply .circuit unless .bothrelays 4 Aand l are: .simultaneously operated. The y,purpose of thatproyision-willbe made clear. hereinafter. A cam 8 which is-operated by-a clock mechanism so as to Vmake one revolution `per minutehas, upon,its periphery, eight-notches similar to the .one represented and sopositioned togeiiect` the .closing of thecontact Si every .seven-andone-half seconds.. andsto maintain .such contact `closed throughout aperiodv ranging from ,.4 to ..57 seconds. The contact '9 is openedandiclosed bythe .movement of themembers I .and H andtheclosingoropening.: of that contact controls .the .operation ofthe relay |25.zRelaysvl. and. il'operatein sequence afterthe operation'otrelayl ontheodd vclosure of contact v9, and remain operatedk .until Lthe 'succeedingeven closure. Relay l idoes. not operate until .relay I2 releases on.the `odd opening rof contact 9v andi remains operated .until thelsucceeding even `.opening of contact 9. Relay t6, which iiscontrolledxby relay I5,in turn controls along'` with relay l4,;the .lampI] which, by :its lighting and 'lthe Lextinction of itslight,y indicatestothe operator. the beginning and the end of the period during which theoral announcement must Vbe 1made; Relay yI6 also controls. lrelay 118.Relay :1.8controls relays llwand -which disconnect` the speech'transmission branch .from the supply circuit andl connect vthereto fthetone transmission branch. lConnected acrossV the leads |2-9 that extend:to the supply circuits 2,0 .is a volume indicator-21., Which assists the.operator in adjusting the amplifier 3 bythe 'volume' control The .leadsI9 `are connected :to the outgoing supply circuit to which may be .at-ytached a plurality :of trunks by means .of Vthe repeating coils-2i and22. Only tWo trunks have `loeenvz'shoWn 'but .it'is vto be `vunderstoodthat any number may be employed within the .limitsrot thefamplier.

.The trunk .23extends tol thel central *oce 1BV and is connected thereatto the amplifier 24 by means of the repeating coil 25. While thatamplifier may be of any type, the form chosen for describing the presentinvention is a simplified arrangement .of that shown in the copendingapplication of Gannett and Lewis, Serial No.

of the time information. Also, connected to theY supply circuit throughthe key 33 is a direct current meter 34 having associated therewith arectier 35 which may be of any type but preferiably is of thecopper-oxide type. A resistance 36 is included in series with the meterand there is shunted across the terminals of the measuring circuit aresistance 31.

'Ihe trunk 38 may extend to a terminating office or an intermediate olcedesignated C. If a terminating oice, it would have thereat appar'- atussubstantially like that shown at central ofce B. If an intermediateoiiice, it would have a repeater and a plurality of inter-amplifiertrunks extending to distant terminating oflices. Such intermediateoflice would also have a transmission level measuring set connectedacross the supply circuit similar to that shown at oice B.

Let it be assumed that the cam 8, rotating in the direction of thearrow, is so positioned that the member I I has fallen with the arrivalof an odd notch and effected the closing of the contact 9. This operatesrelay I2 and thereupon the circuit is closed through the winding ofrelay I3, which circuit includes the battery 39, resistance 4B, Windingof relay I3, conductor 4I, contact 42 and the grounded contact of relayI2. The operation of relay I3 causes the operation of relay I4 which, inturn, causes the locking up of relay I3 through contact 43 of relay I4.The operation of relay I3 not only closes its upper contact to put aground upon relay I4, but also opens its lower contact thereby removingground from the contacts of relay I3. Relay I5 does not operate at thistime because the winding of that relay is shunted by the path thatincludes conductors 44 and 45 to the grounded contact of relay I2. Thatsituation persists for about .5 second, which is the time required forthe cam to move suliiciently to permit the left-hand member I to dropand cause the opening of contact 9. This releases relay I2, which inturn, removes the shunt around the winding of relay I5 and permits thatrelay'to be energized by current ilowing from the battery 39 throughresistance 46, winding of relay I5, conductor 4I and contact 43 toground. The closing of the upper contact of relay I5 puts a ground uponthe circuit that operates relay I6 which, in turn, operates relay I8.The closing of the contacts of relay I8 does not effect the operation ofrelays 4 and 1, because owing to the continued operation of relay, I3,there is no ground upon the circuit that includes the windings of 4and 1. The operation of relay I6 causes the lighting of the lamp I1,which Y is a signal to the operator to begin the making signal, the timewill be three, nine and one-half. The making of that oral announcementwill consume about seven and one-half seconds, at which time the nextsucceeding even notch on the periphery of the cam will come under themember II, causing the closing of the contact 9. This operates relay I2and puts a ground on conductor 45. Since, at this instant, relay I5 isenergized, a circuit is established from battery 39 that includesresistance 40, conductor 41, the lower inner contact of relay I5 andconductor 45 to ground. The path just traced shunts the winding of relayI3 and thereby releases that relay. This releases relay I4 whichextinguishes the operators announcement lamp. The closing of the lowercontact of relay I3 puts a ground upon the circuits of windings ofrelays 4 and 1 and thereby causes the operation of those relays, whichdisconnects the speech transmission branch from the leads I9 andconnects to the latter the tone transmission branch which makes knownthe exact instant of time mentioned by the operator in her oralannouncement. The release of relay I4 sets up a condition such that whenmember IB comes to the notch, opening contact 9, relay I5 will bereleased. The opening of the upper contact of relay I5 releases relay I6and therefore releases .relay I8. The releasing of the latter relay inturn releases relays 4 and 1, thereby disconnecting the tone branch fromthe leads I9 and restoring the connection of the speech transmissionbranch. The purpose of relay 1 is to keep the 80G-cycle tone away fromthe speech transmission branch during the making of the oralannouncement and thus to prevent misunderstandings that might resultfrom the inductive pick-up of the 800- cycle tone during the making ofannouncements.

The relays of the time announcement circuit are now in normal,unoperated condition and continue so until the next notch on theperiphery of the cam comes under the member II, whereupon the cycle ofoperation, -hereinbefore described, will be repeated. It will thus beseen that such provides for the making of announcements every fifteenseconds.

When a subscriber dials or gives the operator the number assigned to thetime announcement networks the machine switching equipment or theoperator will immediately connect the subscribers line to a set ofsubscribers terminals of the time system. The connection will becompletely made in the time system only if no announcement is inprogress. Otherwise the connection to the output of the terminatingampliiier will be kept open until the next seven and one-half 'seconds'interval between lannouncements. During the waiting period a ringingsignal is sent to the subscriber. The details of the accomplishment ofthis connection synchronism are not important to the invention hereindescribed.

In order to give eicient service by such a time announcement system andto insure the clear reception of time information by every subscriberwithin the area supplied by the system, it is essential to test thesystem frequently in order to know whether the transmission levels atvarious points upon the system are sufciently high to give satisfactoryservice. In the making of such tests upon commercial telephone circuits,it is necessary to withdraw the circuit from active service. This may bedone because there are generally suflicient spare facilities. Owing tothe cost of a time announcement system, duplication of its circuits andequipment cannot be justied, so that all tests must be made upon such asystem during its 'period of operation. The measurements are made by anattendant at the time bureau and also at each of the central oices atwhich the repeaters are located. The determination of the condition ofthe system, from the transmission standpoint, is made by measuring themagnitude of the relatively short impulse of 80G-cycle current that is Ydirect current galvanometer movement with a bridge-type copper-oxiderectifier network which provides full-wave rectication. Seriesresistance is included to obtain the correct sensitivity and to reducethe effects of temperature variation on rectifier characteristics. Suchmeasuring systems are suiciently sensitive 'and fast toI allow themaking of a measurement of the transmission level of the signal currentof extremely short duration. The'meter needle will be deflected and willmomentarily come to rest at the steady-state position which is thentaken as the reading of the meter. signal may vary from .2 to .8 second,it may be necessary tov make several observations to insure that thetone signal is long enough to correctly show the steady-state level. Therectifier type meters are required to have such damping characteristicsthat steady-state condition can be obtained with a time signal durationof about .4 second.

For a tone signal of proper intensity, the signal voltage across thesupply circuit 20 must be about .6 of a volt, which is taken as thereference level for subsequent tests. That voltage is adjusted by meansof the potentiometer 6 in the tone transmitting branch. Likewise, theintermediate and terminal ampliers' areadjusted to give the samevoltages across every output. In making the tests upon terminalamplifiers, a lohm resistance 3'! is connected a-cross the supplycircuit 26 by the operation of the key 33.

Since the aforedescribed tests may be made without causing anyinterruption or disturbance in the time announcement system, such testsshould be made frequently in order to afford a substantially continuousindication of the transmission condition of the system as a whole.Obviously, the method which uses the tone signal current for thedetermination of the transmission condition is ideal for employment in atime announcement system which, by its very nature, is continuously usedthroughout the day. While the invention has been described as embodiedin a particular form, it is capable of employment in other and differentforms without departing from the spirit and scope of the appendedclaims.

What is claimed is:

1. In a time announcement system characterized by an oral announcementof the time, followed by the transmission of a tone indicating the exactsecond, the method which consists in Since the time listening in uponthe system at various points' the'reof during the making of the oralannouncements, and, at the termination thereof, connecting transmissionlevel measuring apparatus to the system at the said points and notingthe level at the Ysaid points resulting from the transmission of thesignal tone over said system.k

2. In a time announcement system characterized by an oral announcementof the time, followed by the transmission of a tone indicating the exactsecond, the method which consists in Y listening in upon the systemduring the making of oral announcements, and, at the termination thereofusing the signal tone to measure the transmission efliciency of the saidsystem.

3. In a time announcement system characterized by an oral announcementof the time, followed by the transmission of a tone indicating the exactsecond, the method which consists in transmitting over said system anoral announcement of what the time will be when a given signal istransmitted over said system, transmitting a signal tone to indicate theexact instance of time announced, determining, by listening, the

cessation of said announcement and measuring the amplitude of the signaltone at a given point n on the system.

4. In a time announcement system characterized by an oral announcementof the time, followed by the transmission of a tone indicating the exactsecond, the combination with a transmitting branch4 including atransmitter, an amplifier and a volume control device connectedtherewith, a tone circuit including an` oscillator and a potentiometerconnected therewith, a supply circuit, a transmission line having anamplier connected therewith, over which the spoken announcement and thesignal tone are to be transmitted, the said transmission line beingconnected to said supply circuit, a switch to connect said transmittingbranch and said tone circuit in sequence to said supply circuit, thesaid switch having a timing device to control the duration of connectionof said transmitting branch and said tone circuit to said supplycircuit, a transmission indicating device comprising a D. C. meter, arectier and a resistance adapted to be connected across said supplycircuit whenever said tone is being transmitted to indicate thetransmission level of said tone in the supply circuit, and a secondindicating device connected across the output of the amplier in thetransmission line and also operable upon the transmission of said toneto indicate the level across said output.

5. In a time announcement system characterized by an oral announcementof the time, followed by the transmission of a tone indicating the exactsecond, the combination with a transmission line having a repeaterconnected therewith of a time announcement arrangement comprising aspeech transmitting branch including a transmitter and a repeater, atone transmitting branch including an oscillator and a potentiometer,switching means to connect in sequence and for a predetermined intervaleach of said branches to said transmission line and. means responsive tothe Ycurrent transmitted by said oscillator, during its period ofapplication to said transmission line to indicate the level oftransmission at the output of each of said repeaters.

BENJAMIN F. LEWIS.

